Hello everyone this is my first post on this forum because I have not found a solution in my research. I have a 1994 base model corvette with the zf6 trans, the car has ~80,000 miles now. I bought it with 70,000 miles around 7 months ago. Around 2,000 miles ago it started having a weird idle issue where it would drop to maybe 400 rpm and then kick back up to 1,300 and would either go back to normal or stall the engine out but I was always able to restart. Also when driving on the interstate the car would have sudden jerk where it felt like for a split second the engine was turned of and then on again. Shortly after getting these symptoms I got a check engine light for codes 36 and 62. Which from what I understand is a code for Opti high res signal failure and something to do with the oil temp sensor. I then got a Petris Opti spark and replaced the Opti and vented it + water pump + water temp sensor + thermostat + spark plugs + wires + pcv hose + valve cover gaskets. After replacing all of that I started it up to check everything and bleed coolant I got a check light for code 64 (something to do with O2 sensor) but all other codes where gone. I restarted the car and it went away and hasn't shown up since. About a week after getting it back on the road it has started to have the same issue with erratic idle and stalling. Is the new Opti possibly bad already or is there another issue? Any help would be appreciated!

 

I would rent/buy a fuel pressure gauge and check your fuel pressure. You can tape it to your windshield and drive it to see what is going on when it hesitates or stalls.

 

I have replaced the fuel pump too I forgot to mention that. I will try and look for a fuel pressure gauge to test it tho.

 

I would replace both upstream O2 sensors with NTK21006 $28 each from Rockauto.
https://www.rockauto.com/en/catalog/...2)+sensor,5132

Also, just as a maintenance item, have you pulled any of the spark plugs to check the gap?

 

Check the ignition control module and idle air control Valve.

 

When at idle position the blades in the throttle body close and the air going into the engine passes through the IAC (Idle Air Control). This is a solenoid mounted on the throttle body that regulates the amount of air going into the engine when the blades are closed. These can fail or the passage can get clogged and dirty. Removal is a little tight but workable. One plug to undo and remove it.

 

I replaced the spark plugs and wires and set them to the correct gap, I will look into replacing the 02 sensors

 

How would I go about checking the ICM and the idle air control valve?

 

When I take it out how would I test to make sure that it is not working?